Properly inserting cross-references for supra and infra citations will allow you to easily update all of these citations at any time, even after you have added numerous additional footnotes.
This is a much more efficient method of updating footnote numbers in supra and infra citations than manually changing each of them individually.

Inserting a cross reference:
- Place your cursor at the point in the footnote where you want the note number to appear.
- Go to "References," then click "Cross-reference."
- Change the “Reference type" dropdown to "Footnote" and leave the “Insert as hyperlink” box checked.
- Select the footnote you are referring back to from the list of all the footnotes in the document ("For which footnote") and click "Insert."
Updating all cross references in a document:
- Select "Edit – Select All" (or press CTRL + A) when your cursor is below the line (i.e., in the area where the footnotes are listed, not in the main body of the text).
- Press F9 or right click and select "Update Field."
- Any cross references that were improperly linked will indicate "Error! Bookmark Not Defined."